Mary was born in December 1542 in Linlithgow Palace, the only child of James V of Scotland and his French wife, Mary of Guise. When she was six days old her father died and she became queen. Her mother acted as regent in her stead.
At just five years of age Mary was betrothed to Henry VIII's son, Edward. But her Catholic guardians were opposed to the match and took the young Mary to Stirling Castle, breaking the agreement. Henry ordered a series of savage, yet unsuccessful raids into Scotland known as 'The Rough Wooing'.
At the French court
Conscious of the benefits of an alliance with France, the Scots betrothed the young queen to Francis, the four-year-old heir to the French crown, and sent Mary to be raised at the court of Henry II. In April 1558, the young couple were duly married and Francis became king in 1559, briefly uniting the French and Scottish crowns. However, Henry died from an ear infection the following year.
A widow at just 18, Mary returned to Scotland where she faced many challenges. As a Catholic in a country that was officially Protestant, she was regarded with suspicion by some of her subjects. Mary accepted the Protestant-led government and initially ruled with moderation.
Earl of Darnley's murder
In 1565, Mary married her cousin the Earl of Darnley. Their relationship quickly broke down and as the spoiled and petulant Darnley spent less time with Mary, she became increasingly close to her advisor, the Earl of Bothwell.
In March 1566 Darnley and a group of Protestant nobles murdered Mary's Italian secretary, David Rizzio. They claimed Rizzio was having an affair with Mary and was using this as leverage to gain influence in court. Darnley and the nobles burst in upon the heavily-pregnant Mary as she was having supper with Rizzio and five close friends, including Bothwell. The group dragged Rizzio from the table into the next room and stabbed him 56 times.
After the birth their son, James in June 1566, Darnley and Mary's relationship continued to deteriorate. In February 1567, there was an explosion at the house where Darnley was staying just outside of Edinburgh. His body was found outside, giving rise to speculation that he had escaped the blast but had then been murdered.
By waiting a mere three months before marrying the Earl of Bothwell – the chief suspect in Darnley's murder – Mary turned the Scottish nobility against her. Bothwell was exiled and Mary forced to abdicate in July 1567. She was imprisoned in Lochleven Castle, Kinross-shire and her infant son James was made king.
Having escaped from Lochleven in 1568, only for her army to be defeated at the Battle of Langside near Glasgow, Mary fled to England to seek refuge from her cousin, Elizabeth I.
Mary had hoped Queen Elizabeth would support her cause but her arrival in England put her cousin in a difficult position. The Catholic Mary also had a strong claim to the English throne so Elizabeth had her imprisoned and kept under surveillance.
Over the next 19 years, Mary became the focus of numerous Catholic plots to assassinate Elizabeth and put her on the English throne. As Mary was not directly involved in these plots Elizabeth was reluctant to act against her.
Then in 1586, Mary corresponded with Anthony Babington who was plotting to depose Elizabeth. This was to be her downfall. The letters were intercepted by Elizabeth's spymaster Francis Walsingham. This was the evidence he needed to convince Elizabeth that, while she lived, Mary would always be a danger. Mary was tried for treason and condemned to death in October 1586.
Elizabeth prevaricated over signing the death warrant, but eventually did and Mary was executed at Fotheringhay Castle, on 8 February 1587 at the age of 44.
Mary's son James went on to succeed Elizabeth in 1603. In 1612 he had his mother's body exhumed from Peterborough Cathedral and placed in the vault of King Henry VII's Chapel in Westminster Abbey.
Source : https://www.bbc.co.uk/history/people/mary_queen_of_scots689